Reduced mating efficiency due to osteo-arthrosis in a ram.

An apparently clinically normal ram with excellent semen quality, an intact pituitary-testicular axis and good libido displayed abnormal mounting behaviour when subjected to a mating test with 3 oestrus ewes. The ram adopted a peculiar mounting stance, he moved backwards several paces and then lunged forward becoming momentarily airborne in an attempt to mount. After a number of these airborne attempts at mounting the ram managed one successful service, striking the ewe with his sternum while airborne. At completion of the service the ram lost all sexual interest in the other two oestrous ewes. Radiographs revealed a chronic osteo-arthrosis of the right femero-tibial joint. It was concluded that the osteo-arthrosis caused the ram to suffer a great deal of pain interfering with his mounting ability which in turn affected his mating efficiency and serving capacity severely.